1. Field of the Invention
The present invention relates to an illuminator for emitting lights having directivity in at least tow directions, and a display apparatus whose display panel is backed by this illuminator.
2. Description of the Related Art
Conventionally, edge-light type backlights have been known as illuminators for display panels. This type of backlight is built up of a light guide made of a transparent plate and a light source, wherein one end surface of the light guide serves as a light entrance surface for a light from the light source to enter, and one plate surface of the light guide serves as a light exit surface from which the light absorbed from the one end surface goes out, and wherein the light source is disposed so as to face the one end surface of the light guide. Light from the light source is let into the light guide from the light entrance surface and guided inside the light guide while being repetitively reflected on the light guide, so as to be let out from almost the entire surface of the light exit surface.
On the other hand, as a display apparatus using a display panel, there is proposed an apparatus which displays two different images on one display panel, one of which images is viewable when the display panel is viewed from the right hand side of the display panel, and the other one of which images is viewable when the display panel is viewed from the left hand side thereof.
Such a display apparatus is used for, for example, a car navigation system for displaying a navigation image when the display is seen from the driver's seat, while displaying a different video when the display is seen from the front passenger's seat. Such a display apparatus is also used for displaying two images having a parallax corresponding to the left and right eyes of the viewer on one display, so as to let a right eye image, which is to be viewed from the right hand side of the display apparatus, be recognized by the right eye of the viewer, and a left eye image to be viewed from the left hand side of the apparatus be recognized by the left eye of the viewer, thereby displaying a three-dimensional image.
Liquid crystal display apparatuses for displaying such three-dimensional images include an apparatus for displaying the left eye image by pixels on every other row while displaying the right eye image by pixels on remaining every other row, and distributing the light from pixels on every other row and the light from pixels on remaining every other row toward the left and right eyes of the viewer respectively by using a lenticular lens so that the left eye image and right eye image reach the intended eyes (Unexamined Japanese Patent Application KOKAI Publication No. H3-119889), or an apparatus for making the images be viewed by the left eye and right eye of the viewer via a parallax barrier in which a plurality of stripe-shaped transmissive portions and light opaque portions, which are parallel with the rows of pixels of the liquid crystal display panel, are disposed alternately (Unexamined Japanese Patent Application KOKAI Publication No. H7-005455 and Unexamined Japanese Patent Application KOKAI Publication No. H10-268230).
However, since such a display apparatus for displaying two images on one display panel displays one image by pixels on every other row of the display panel and displays the other image by pixels on remaining every other row, each image has a low resolution, therefore images having a satisfactory image quality cannot be displayed.
Furthermore, a lenticular lens having a lens pitch corresponding to the pixel pitch of the display panel, or a parallax barrier having a transparency pitch corresponding to the pixel pitch needs to be disposed such that each lens unit or each transparent portion will be in a predetermined positional relation with respect to the pixels on each row of the display panel with sufficient precision, making the display apparatus hard to manufacture.